Brain Benefits of L-Theanine

There’s been a resurgence of interest in the anxiety-relieving powers of L-theanine, an
amino acid found in green tea.1

Discoveries over the past two years have uncovered exciting additional properties of this nutrient best known
for inducing calming, tranquilizing effects
while simultaneously improving alertness.

In this Research Update, we examine how L-theanine acts in the brain, and review compelling new studies on
its actions that include potentially reduced
risk of stroke and less brain damage if an ischemic stroke were to occur.

What you need to know

Stress can severely impact your quality of life and increase the risk of death. L-theanine, an amino acid naturally
found in green tea, has been shown in several studies to de-stress the body, resulting in a decreased risk of related
diseases. Exciting results show that L-theanine works by decreasing the binding of the excitatory neurotransmitter
glutamate to its receptors and stimulating production of the inhibitory neurotransmitter GABA. The chemical imbalances
between these neurotransmitters are contributing factors to a range of brain related diseases and cognitive decline. An
interesting study showed that L-theanine decreases the expression of an inflammatory molecule responsible for
artery-blocking clots that result in a stroke. Clinical studies reveal that L-theanine supplementation decreases anxiety
in schizophrenic patients and improves sleep quality. Learn more about L-theanine’s benefits in this article.

How L-Theanine Works in the Brain to Block Anxiety and Stress

L-theanine relieves anxiety in large part because it bears a close resemblance to the brain-signaling
chemical glutamate. L-theanine produces the opposite
effect in the brain.

While glutamate is the brain’s most important excitatory neurotransmitter, L-theanine binds to the
same brain cell receptors and blocks them to
glutamate’s effects. This action produces inhibitory effects.1,2 That
inhibition to brain overactivity has a calming,
relaxing effect in which anxiety fades.3

In addition to blocking excitatory stimuli at glutamate receptors in the brain, L-theanine also stimulates
production of the inhibitory, relaxing
neurotransmitter GABA, adding to its calming, anti-anxiety effects.2

Unlike prescription anti-anxiety drugs, however, some of which mimic GABA’s effects, L-theanine produces its
anti-anxiety effects without producing
sleepiness or impairing motor behavior.4 In fact, L-theanine has been shown in human studies to
moderately improve alertness and attention while
exerting its anxiety-reducing effects.5

Of particular interest are studies showing that L-theanine supplementation prevents the
abrupt rise in blood pressure that some people experience under
stress.1 The reason this is so critical is that many people have normal blood
pressure readings at rest that spike up to dangerously high levels when subjected to stressful situations.

These periods of surging blood pressure inflict massive arterial damage and are the main reason why at-home
and at-office blood pressure testing are so
important.

New Directions for L-Theanine

Scientists are now increasingly interested in applications for L-theanine far beyond its anti-anxiety
properties. Excessive glutamate stimulation of brain
cells (excitotoxicity) is a factor in development of long-term neurodegenerative disorders, stroke,
and schizophrenia.6,7 Therefore,
L-theanine’s glutamate-blocking capabilities make it promising for neuroprotection and prevention in these
areas.

And while its deeper mechanisms are still under investigation, there is tantalizing evidence that L-theanine
influences expression of genes in brain areas
responsible for fear and aggression (amygdala) and memory (hippocampus), helping to balance the behavioral
responses to stress, and potentially improve
conditions such as mood disorders, post-traumatic stress disorder (PTSD), and substance
dependence.8

L-Theanine Protects Brain Cells and Promotes Cognitive Function

There’s a link between anxiety, reaction to stress, and the brain’s most fundamental function, maintaining
cognition. Studies over the past two years
suggest a potential role for L-theanine in supporting cognitive function and preventing its loss.

Stress has powerful negative effects on one’s ability to think clearly and make smart decisions. This is
demonstrated physiologically by animal experiments
showing that stress significantly reduces animals’ performance on standard tests of learning and memory, as
well as by increased oxidative stress in the
brain and elevated blood levels of stress-response hormones such as catecholamine and adrenaline. Treating
animals with L-theanine before the stress
is applied, however, results in reversal not only of cognitive impairment, but also of the elevation of
stress hormones and oxidative damage.9

Studies such as these demonstrate that L-theanine can specifically reduce the molecular impacts of acute
stress, and the resulting excitotoxicity,
on brain cells.10,11 The issue with chronic glutamate-driven excitotoxicity is profound and
long-lasting cognitive dysfunction, including
neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s diseases, and amyotrophic lateral
sclerosis (ALS).12

The protective effects of L-theanine have been shown in animal models for at least the first three of these
disorders, suggesting that regular L-theanine
supplementation might be important in fending off these tragic conditions by opposing the destructive
effects of long-term glutamate excitotoxicity.13-16

In a rat model study for Huntington’s disease, researchers investigated the protective effects of L-theanine
against 3-nitropropionic acid (3-NP).
Rats exposed to 3-nitropropionic acid experienced significant reductions in body weight, oxidative defenses,
and locomotor activity, as well as impaired
mitochondrial enzyme activity. But when exposed to L-theanine, the behavioral, biochemical, and
mitochondrial enzyme activities were significantly
attenuated, leading authors to conclude that “L-theanine has neuroprotective activity against
3-nitropropionic acid induced neurotoxicity.”17

Exposure to toxic chemicals is another known risk factor for many of the neurodegenerative disorders, with
the metal aluminum being a major culprit.18,19 Recent studies show that L-theanine is capable of
preventing both the biochemical and structural damage to brain cells induced by
aluminum, offering yet another means by which this nutrient can prevent or slow cognitive
decline.20

Taste the Relaxation

The molecular similarity of L-theanine with glutamic acid can be experienced simply by tasting it.
L-theanine provides the umami flavor that gives
green tea its richness.31 One of the more common molecules that delivers umami taste is
glutamic acid, and studies show that glutamate and
L-theanine both stimulate the same receptors on our tongues, in a vivid demonstration of molecular
mimicry.32,33

In the brain, of course, the similarity is only close enough for L-theanine to bind to brain
glutamate receptors but without stimulating them, which is why
L-theanine produces relaxing, as opposed to stimulating, effects.

L-Theanine Reduces Stroke Impact

A stroke is the result of a sudden blockage of blood (ischemia) to a part of the
brain, resulting in massive chemical stresses,
extreme excitotoxicity, and eventual death of brain cells.21 The latest studies show that
L-theanine has properties that may both help to
prevent strokes and to mitigate the damage caused when they do occur.

Lab studies show that L-theanine is capable of significantly improving nitric oxide
production in endothelial (artery-lining)
cells.22 This has the potential to lower stroke risk because nitric oxide is a signaling molecule
that endothelial cells use to communicate
information about blood flow and pressure to muscles in the artery walls, telling them to constrict or relax
appropriately in response and distributing
blood flow appropriately.

In another stroke-preventing mechanism, L-theanine has recently been shown to significantly reduce the
expression of adhesion molecules to the endothelial
wall by inhibiting tumor necrosis factor alpha (TNF-a), thereby reducing the risk of an
artery-blocking clot or obstruction that produces a
stroke.23

L-theanine protects the body from the damage of blood reperfusing, or refilling that occurs after the abrupt
loss of circulation during the stroke.24

This ischemia-reperfusion injury results in massive release of glutamate and
produces deadly excitotoxicity.25

Animal studies show that administration of L-theanine up to 12 hours after a stroke is induced protects
brain cells and reduces the size of the damaged
brain areas. Even treatment as late as 24 hours after the stroke improves neurological status.24

L-Theanine May Play a Role in Ameliorating Schizophrenia

Schizophrenia, literally a “split mind” in which sufferers experience a cut-off from reality, is one of the
most tragic and misunderstood disorders known.
People with schizophrenia may experience positive symptoms such as hallucinations,
delusions, and paranoid thinking, as well as negative symptoms including loss of
ability to experience pleasure, blunted emotions, and diminished speech capacity.26

Perhaps because schizophrenia may involve excitotoxic damage to brain cells, L-theanine has recently been
the focus of human studies in patients with this
disease.27

In one study of 40 patients with schizophrenia, subjects were given placebo or 400 mg
L-theanine along with their regular medications for
an eight-week trial. The supplemented patients demonstrated significant reductions in their anxiety and
general symptoms of psychopathology.28

A 250 mg per day dose of L-theanine significantly improved, in a different study scores on
positive symptoms, as well as in sleep quality.29 And the combination of L-theanine (400
mg per day) with the hormone pregnenolone (50 mg per day) was
capable of reversing not only anxiety, but also negative symptoms.30

Summary

L-theanine, an amino acid found in green tea, reduces anxiety by blocking excitatory stimuli at glutamate
receptors in the brain while stimulating
production of the inhibitory, relaxing neurotransmitter GABA. But unlike prescription anti-anxiety drugs,
L-theanine relieves stress without causing
drowsiness or impairing motor behavior. In fact, studies show it improves alertness and attention.
Researchers are now examining L-theanine’s applications
beyond its anti-anxiety effects. Studies suggest a role for L-theanine in supporting cognitive function and
preventing cognitive loss by protecting brain
cells and preventing strokes and reducing the damaging effects if a stroke has occurred. Lastly, L-theanine
is the subject of human studies in patients
with schizophrenia.

If you have any questions on the scientific content of this article, please call a Life
Extension® Wellness Specialist at 1-866-864-3027.

Exley C. Why industry propaganda and political interference cannot disguise the inevitable role played
by human exposure to aluminum in neurodegenerative
diseases, including Alzheimer’s disease. Front Neurol. 2014;5:212.

Additional Information

This supplement should be taken in conjunction with a healthy diet and regular exercise program. Individual results are not guaranteed and results may vary.

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